The invention relates to an integrated gas control and safety valve for a burner of a modulatable gas heating device which is configured to adapt to a changeable thermal load and to abruptly turn off the gas flow, in particular for heating living areas and for gas heaters that supply hot water.
Gas control and safety valves of this type typically include two electrically controllable actuator units, namely a rapidly closing valve and a modulation valve. The two independently operating actuator units are operated by electromagnets and are closed in the de-energized state by return springs. For modulating the gas flow, the modulation valve is additionally fine-adjusted by a proportional magnet or a stepper motor, so that two rapid closure functions and a modulating function can be realized with two actuator units.
DE 103 18 569 B3 discloses a gas control and safety valve for burners of a modulatable gas heating device with two closure elements positioned in a housing in coaxial arrangement between an inlet channel and an outlet channel. The first, outer closure element include a drive axle, a throttle element arranged on the lower end of the drive axle, and a pre-biased spring element operating on the first closure element and arranged in the upper region of the drive axle. The second, inner closure element arranged between the first spring element and the throttle element has a sealing element connected with a hollow armature, wherein the sealing element seats on a valve seat for closing an annular gap connected with the outlet channel. The hollow armature is movable in a cylindrical cavity surrounded by the drive winding of the hollow armature and arranged so as to operate against the force of a second pre-biased spring element.
DE 101 14 175 C1 describes a coaxial magnetic valve, wherein the magnetic drive has two independent, axially superpositioned magnetic circuits, each including a coil, which cooperate with the two superpositioned armatures, wherein one of the armatures is connected with the inner valve disk and the other armature is connected with the outer valve disk, wherein the armature of the outer valve disk is penetrated by a push rod connecting the inner valve disk with its armature.
DE 198 26 076 C1 describes an invention with a dual safety valve. The first (outer) valve disk in the flow direction of the dual safety valve surrounds the second (inner) valve disk, so that both valve seats are combined into a common valve seat and this valve seat surrounds the only valve opening. This dual safety valve also includes a coil which operates on an armature connected with the inner valve disk. The outer valve disk engages behind the inner valve disk in the closing direction and is hence carried along by the inner valve disk, when the inner valve disk opens. This invention has the disadvantage that both valve disks can only be opened together, thereby preventing the two actuators from operating independently.
DE 195 25 384 C2 and the almost identical EP 0 757 200 B1 disclose a dual safety magnetic valve with two actuators. The two actuators are arranged on a common axis, preferably one on top of the other, wherein the first actuator has as a magnetic armature a hollow armature. The armature of the second actuator is longitudinally movable inside the hollow armature along the common axis, wherein only a single magnetic drive, in which the hollow armature as well as the armature protrude, is provided for both actuators. Although this dual safety valve already has a relatively compact design, the axial dimensions are still large because the valves disks and actuators are both movable and arranged consecutively in the axial direction.
DE 103 61 918 A1 describes a gas-tight valve drive with a motor and a safety closure function, wherein the stepper motor used for the valve drive consists of a rotating rotor with an integrated spindle-nut system for converting the rotary movement into a translational displacement and as a spindle an adjusting rod coupled with a valve cone. When the rotor rotates, the adjusting rod moves along the motor axis in the hub through an integrated looking piston in the valve body. A return spring provides a safety adjustment function. This invention is characterized in that the valve drive consists of a motor part and a valve part with a continuous adjusting rod, that the return spring is implemented as a coil spring and located on the drive side of the motor and is coupled as a first element of the valve part following the coupling element with the valve body receiving the return spring and via the coupling element with the rotor of the motor part.
Disadvantageously, due to the large number of components, conventional gas valves have large tolerance chains or interfering actuating paths which require a complicated installation and may also increase the failure rate.
Another major disadvantage of conventional gas valves is that the sealing sleeve required for external gas-tightness limits the mechanical efficiency of the actuators of the gas valves.